@@ -5,6 +5,7 @@ set(CMAKE_C_FLAGS_DEBUG "-g -Wall -Wextra -std=gnu99")
 set(CMAKE_C_FLAGS_RELEASE "-O3 -Wall -Wextra -std=gnu99")
 set(USE_CLI_DEBUGGER ON CACHE BOOL "Whether or not to enable the CLI-mode ARM debugger")
 set(USE_GDB_STUB ON CACHE BOOL "Whether or not to enable the GDB stub ARM debugger")
+set(USE_FFMPEG ON CACHE BOOL "Whether or not to enable FFmpeg support")
 set(BUILD_SDL ON CACHE BOOL "Build SDL frontend")
 set(BUILD_PERF ON CACHE BOOL "Build performance profiling tool")
 file(GLOB ARM_SRC ${CMAKE_SOURCE_DIR}/src/arm/*.c)
@@ -96,6 +97,15 @@ add_definitions(-DUSE_GDB_STUB)
 	list(APPEND DEBUGGER_SRC ${CMAKE_SOURCE_DIR}/src/debugger/gdb-stub.c)
 endif()
 source_group("ARM debugger" FILES ${DEBUGGER_SRC})
+
+if(USE_FFMPEG)
+	pkg_search_module(LIBAVCODEC libavcodec REQUIRED)
+	pkg_search_module(LIBAVFORMAT libavformat REQUIRED)
+	pkg_search_module(LIBAVUTIL libavutil REQUIRED)
+	add_definitions(-DUSE_FFMPEG)
+	list(APPEND UTIL_SRC "${CMAKE_SOURCE_DIR}/src/platform/ffmpeg/ffmpeg-encoder.c")
+	list(APPEND DEPENDENCY_LIB ${LIBAVCODEC_LIBRARIES} ${LIBAVFORMAT_LIBRARIES} ${LIBAVUTIL_LIBRARIES})
+endif()
 
 find_package(PNG REQUIRED)
 find_package(ZLIB REQUIRED)

@@ -704,6 +704,10 @@ GBASyncLockAudio(audio->p->sync);
 	CircleBufferWrite32(&audio->left, sampleLeft);
 	CircleBufferWrite32(&audio->right, sampleRight);
 	unsigned produced = CircleBufferSize(&audio->left);
+	struct GBAThread* thread = GBAThreadGetContext();
+	if (thread && thread->stream) {
+		thread->stream->postAudioFrame(thread->stream, sampleLeft, sampleRight);
+	}
 	GBASyncProduceAudio(audio->p->sync, produced >= CircleBufferCapacity(&audio->left) / sizeof(int32_t) * 3);
 }
 

@@ -559,6 +559,9 @@ thread->rewindBufferNext = thread->rewindBufferInterval;
 			GBARecordFrame(thread);
 		}
 	}
+	if (thread->stream) {
+		thread->stream->postVideoFrame(thread->stream, thread->renderer);
+	}
 	if (thread->frameCallback) {
 		thread->frameCallback(thread);
 	}

@@ -39,6 +39,11 @@ Condition audioRequiredCond;
 	Mutex audioBufferMutex;
 };
 
+struct GBAAVStream {
+	void (*postVideoFrame)(struct GBAAVStream*, struct GBAVideoRenderer* renderer);
+	void (*postAudioFrame)(struct GBAAVStream*, int32_t left, int32_t right);
+};
+
 struct GBAThread {
 	// Output
 	enum ThreadState state;
@@ -58,6 +63,7 @@ struct VFile* patch;
 	const char* fname;
 	int activeKeys;
 	struct GBAInputMap inputMap;
+	struct GBAAVStream* stream;
 
 	// Run-time options
 	int frameskip;

@@ -0,0 +1,197 @@
+#include "ffmpeg-encoder.h"
+
+#include "gba-video.h"
+
+#include <libavutil/imgutils.h>
+
+static void _ffmpegPostVideoFrame(struct GBAAVStream*, struct GBAVideoRenderer* renderer);
+static void _ffmpegPostAudioFrame(struct GBAAVStream*, int32_t left, int32_t right);
+
+void FFmpegEncoderInit(struct FFmpegEncoder* encoder) {
+	av_register_all();
+
+	encoder->d.postVideoFrame = _ffmpegPostVideoFrame;
+	encoder->d.postAudioFrame = _ffmpegPostAudioFrame;
+
+	FFmpegEncoderSetAudio(encoder, "flac", 0);
+	FFmpegEncoderSetVideo(encoder, "png", 0);
+	encoder->currentAudioSample = 0;
+	encoder->currentAudioFrame = 0;
+	encoder->currentVideoFrame = 0;
+}
+
+bool FFmpegEncoderSetAudio(struct FFmpegEncoder* encoder, const char* acodec, unsigned abr) {
+	if (!avcodec_find_encoder_by_name(acodec)) {
+		return false;
+	}
+	encoder->audioCodec = acodec;
+	encoder->audioBitrate = abr;
+	return true;
+}
+
+bool FFmpegEncoderSetVideo(struct FFmpegEncoder* encoder, const char* vcodec, unsigned vbr) {
+	AVCodec* codec = avcodec_find_encoder_by_name(vcodec);
+	if (!codec) {
+		return false;
+	}
+
+	size_t i;
+	encoder->pixFormat = AV_PIX_FMT_NONE;
+	for (i = 0; codec->pix_fmts[i] != AV_PIX_FMT_NONE; ++i) {
+		if (codec->pix_fmts[i] == AV_PIX_FMT_RGB24) {
+			encoder->pixFormat = AV_PIX_FMT_RGB24;
+			break;
+		}
+		if (codec->pix_fmts[i] == AV_PIX_FMT_BGR0) {
+			encoder->pixFormat = AV_PIX_FMT_BGR0;
+		}
+	}
+	if (encoder->pixFormat == AV_PIX_FMT_NONE) {
+		return false;
+	}
+	encoder->videoCodec = vcodec;
+	encoder->videoBitrate = vbr;
+	return true;
+}
+
+bool FFmpegEncoderOpen(struct FFmpegEncoder* encoder, const char* outfile) {
+	AVCodec* acodec = avcodec_find_encoder_by_name(encoder->audioCodec);
+	AVCodec* vcodec = avcodec_find_encoder_by_name(encoder->videoCodec);
+	if (!acodec || !vcodec) {
+		return false;
+	}
+
+	avformat_alloc_output_context2(&encoder->context, 0, 0, outfile);
+
+	encoder->audioStream = avformat_new_stream(encoder->context, acodec);
+	encoder->audio = encoder->audioStream->codec;
+	encoder->audio->bit_rate = encoder->audioBitrate;
+	encoder->audio->sample_rate = 0x8000;
+	encoder->audio->channels = 2;
+	encoder->audio->channel_layout = AV_CH_LAYOUT_STEREO;
+	encoder->audio->sample_fmt = AV_SAMPLE_FMT_S16;
+	avcodec_open2(encoder->audio, acodec, 0);
+	encoder->audioFrame = av_frame_alloc();
+	encoder->audioFrame->nb_samples = encoder->audio->frame_size;
+	encoder->audioFrame->format = encoder->audio->sample_fmt;
+	encoder->audioFrame->pts = 0;
+	encoder->audioBufferSize = av_samples_get_buffer_size(0, encoder->audio->channels, encoder->audio->frame_size, encoder->audio->sample_fmt, 0);
+	encoder->audioBuffer = av_malloc(encoder->audioBufferSize);
+	avcodec_fill_audio_frame(encoder->audioFrame, encoder->audio->channels, encoder->audio->sample_fmt, (const uint8_t*) encoder->audioBuffer, encoder->audioBufferSize, 0);
+
+	encoder->videoStream = avformat_new_stream(encoder->context, vcodec);
+	encoder->video = encoder->videoStream->codec;
+	encoder->video->bit_rate = encoder->videoBitrate;
+	encoder->video->width = VIDEO_HORIZONTAL_PIXELS;
+	encoder->video->height = VIDEO_VERTICAL_PIXELS;
+	encoder->video->time_base = (AVRational) { VIDEO_TOTAL_LENGTH, GBA_ARM7TDMI_FREQUENCY };
+	encoder->video->pix_fmt = encoder->pixFormat;
+	encoder->video->gop_size = 15;
+	encoder->video->max_b_frames = 0;
+	avcodec_open2(encoder->video, vcodec, 0);
+	encoder->videoFrame = av_frame_alloc();
+	encoder->videoFrame->format = encoder->video->pix_fmt;
+	encoder->videoFrame->width = encoder->video->width;
+	encoder->videoFrame->height = encoder->video->height;
+	encoder->videoFrame->pts = 0;
+	av_image_alloc(encoder->videoFrame->data, encoder->videoFrame->linesize, encoder->video->width, encoder->video->height, encoder->video->pix_fmt, 32);
+
+	if (encoder->context->oformat->flags & AVFMT_GLOBALHEADER) {
+		encoder->audio->flags |= CODEC_FLAG_GLOBAL_HEADER;
+		encoder->video->flags |= CODEC_FLAG_GLOBAL_HEADER;
+	}
+
+	avio_open(&encoder->context->pb, outfile, AVIO_FLAG_WRITE);
+	avformat_write_header(encoder->context, 0);
+
+	return true;
+}
+
+void FFmpegEncoderClose(struct FFmpegEncoder* encoder) {
+	av_write_trailer(encoder->context);
+	avio_close(encoder->context->pb);
+
+	av_free(encoder->audioBuffer);
+	av_frame_free(&encoder->audioFrame);
+	avcodec_close(encoder->audio);
+
+	av_frame_free(&encoder->videoFrame);
+	avcodec_close(encoder->video);
+	avformat_free_context(encoder->context);
+}
+
+void _ffmpegPostAudioFrame(struct GBAAVStream* stream, int32_t left, int32_t right) {
+	struct FFmpegEncoder* encoder = (struct FFmpegEncoder*) stream;
+
+	av_frame_make_writable(encoder->audioFrame);
+	encoder->audioBuffer[encoder->currentAudioSample * 2] = left;
+	encoder->audioBuffer[encoder->currentAudioSample * 2 + 1] = right;
+	encoder->audioFrame->pts = av_rescale_q(encoder->currentAudioFrame, encoder->audio->time_base, encoder->audioStream->time_base);
+	++encoder->currentAudioFrame;
+	++encoder->currentAudioSample;
+
+	if ((encoder->currentAudioSample * 4) < encoder->audioBufferSize) {
+		return;
+	}
+	encoder->currentAudioSample = 0;
+
+	AVPacket packet;
+	av_init_packet(&packet);
+	packet.data = 0;
+	packet.size = 0;
+	int gotData;
+	avcodec_encode_audio2(encoder->audio, &packet, encoder->audioFrame, &gotData);
+	if (gotData) {
+		packet.stream_index = encoder->audioStream->index;
+		av_interleaved_write_frame(encoder->context, &packet);
+	}
+	av_free_packet(&packet);
+}
+
+void _ffmpegPostVideoFrame(struct GBAAVStream* stream, struct GBAVideoRenderer* renderer) {
+	struct FFmpegEncoder* encoder = (struct FFmpegEncoder*) stream;
+	uint32_t* pixels;
+	unsigned stride;
+	renderer->getPixels(renderer, &stride, (void**) &pixels);
+
+	AVPacket packet;
+
+	av_init_packet(&packet);
+	packet.data = 0;
+	packet.size = 0;
+	av_frame_make_writable(encoder->videoFrame);
+	encoder->videoFrame->pts = av_rescale_q(encoder->currentVideoFrame, encoder->video->time_base, encoder->videoStream->time_base);
+	++encoder->currentVideoFrame;
+
+	unsigned x, y;
+	if (encoder->videoFrame->format == AV_PIX_FMT_BGR0) {
+		for (y = 0; y < VIDEO_VERTICAL_PIXELS; ++y) {
+			for (x = 0; x < VIDEO_HORIZONTAL_PIXELS; ++x) {
+				uint32_t pixel = pixels[stride * y + x];
+				encoder->videoFrame->data[0][y * encoder->videoFrame->linesize[0] + x * 4] = pixel >> 16;
+				encoder->videoFrame->data[0][y * encoder->videoFrame->linesize[0] + x * 4 + 1] = pixel >> 8;
+				encoder->videoFrame->data[0][y * encoder->videoFrame->linesize[0] + x * 4 + 2] = pixel;
+			}
+		}
+	} else if (encoder->videoFrame->format == AV_PIX_FMT_RGB24) {
+		for (y = 0; y < VIDEO_VERTICAL_PIXELS; ++y) {
+			for (x = 0; x < VIDEO_HORIZONTAL_PIXELS; ++x) {
+				uint32_t pixel = pixels[stride * y + x];
+				encoder->videoFrame->data[0][y * encoder->videoFrame->linesize[0] + x * 3] = pixel;
+				encoder->videoFrame->data[0][y * encoder->videoFrame->linesize[0] + x * 3 + 1] = pixel >> 8;
+				encoder->videoFrame->data[0][y * encoder->videoFrame->linesize[0] + x * 3 + 2] = pixel >> 16;
+			}
+		}
+	}
+
+	int gotData;
+	avcodec_encode_video2(encoder->video, &packet, encoder->videoFrame, &gotData);
+	if (gotData) {
+		if (encoder->videoStream->codec->coded_frame->key_frame) {
+			packet.flags |= AV_PKT_FLAG_KEY;
+		}
+		packet.stream_index = encoder->videoStream->index;
+		av_interleaved_write_frame(encoder->context, &packet);
+	}
+	av_free_packet(&packet);
+}

@@ -0,0 +1,40 @@
+#ifndef FFMPEG_ENCODER
+#define FFMPEG_ENCODER
+
+#include "gba-thread.h"
+
+#include <libavcodec/avcodec.h>
+#include <libavformat/avformat.h>
+
+struct FFmpegEncoder {
+	struct GBAAVStream d;
+	AVFormatContext* context;
+
+	unsigned audioBitrate;
+	const char* audioCodec;
+
+	unsigned videoBitrate;
+	const char* videoCodec;
+
+	AVCodecContext* audio;
+	uint16_t* audioBuffer;
+	size_t audioBufferSize;
+	AVFrame* audioFrame;
+	size_t currentAudioSample;
+	int64_t currentAudioFrame;
+	AVStream* audioStream;
+
+	AVCodecContext* video;
+	enum AVPixelFormat pixFormat;
+	AVFrame* videoFrame;
+	int64_t currentVideoFrame;
+	AVStream* videoStream;
+};
+
+void FFmpegEncoderInit(struct FFmpegEncoder*);
+bool FFmpegEncoderSetAudio(struct FFmpegEncoder*, const char* acodec, unsigned abr);
+bool FFmpegEncoderSetVideo(struct FFmpegEncoder*, const char* vcodec, unsigned vbr);
+bool FFmpegEncoderOpen(struct FFmpegEncoder*, const char* outfile);
+void FFmpegEncoderClose(struct FFmpegEncoder*);
+
+#endif